Arguments:

The ID of the connection to the channel to send the message on, which you've
established by calling
ConnectAttach()
or one of its cover functions, such as
name_open()
or
open().

siov

An array of buffers that contains the message that you want to send.

sparts

The number of elements in the siov array.

rmsg

A pointer to a buffer where the reply can be stored.

rbytes

The size of the reply buffer.

Library:

libc

Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.

Description:

The MsgSendvsnc() and MsgSendvsnc_r()
kernel calls send a message to a process's channel via the connection identified by coid.

These functions are identical except in the way they indicate errors.
See the Returns section for details.

The number of bytes transferred is the minimum of that specified
by both the sender and the receiver. The send data isn't allowed
to overflow the receive buffer area provided by the receiver. The reply
data isn't allowed to overflow the reply buffer area provided.

The sending thread becomes blocked waiting for a reply. If the
receiving process has a thread that's RECEIVE-blocked on the channel,
the transfer of data into its address space occurs immediately, and the
receiving thread is unblocked and made ready to run. The sending
thread becomes REPLY-blocked. If there are
no waiting threads on the channel, the sending thread becomes
SEND-blocked and is placed in a queue (perhaps
with other threads). In this case, the actual transfer of data doesn't
occur until a receiving thread receives on the channel. At this point,
the sending thread becomes REPLY-blocked.

Note:
The receiving thread's effective priority might change when you send a message to it.
For more information, see
"Priority inheritance and messages"
in the Interprocess Communication (IPC) chapter of the System Architecture guide.

The message has been sent but not yet received.
If a thread is waiting to receive the message, this state is skipped
and the calling thread goes directly to STATE_REPLY.

STATE_REPLY

The message has been received but not yet replied to.
This state may be entered directly, or from STATE_SEND.

Returns:

The only difference between the MsgSendvsnc() and MsgSendvsnc_r()
functions is the way they indicate errors:

MsgSendvsnc()

Success

The value of status from MsgReply*().

-1

An error occurred
(errno
is set), or the server called MsgError*()
(errno is set to the error value passed to MsgError()).

MsgSendvsnc_r()

Success

The value of status from MsgReply*().

negative value

An error occurred
(errno is NOT set, the value is the negative of a value from the Errors section), or
the server called MsgError*()
(errno is NOT set, the value is the negative of the error value passed to
MsgError()).

Errors:

EBADF

The connection indicated by coid is no longer
connected to a channel, or the connection indicated by coid
doesn't exist. The channel may have been terminated by the server,
or the network manager if it failed to respond to multiple polls.

EFAULT

A fault occurred when the kernel tried to access the buffers provided.
This may have occurred on the receive or the reply.

EHOSTDOWN

The host is down (e.g., a send across Qnet failed).

EHOSTUNREACH

Unable to communicate with remote node (e.g., across Qnet).

EINTR

The call was interrupted by a signal.

EOVERFLOW

The sum of the IOV lengths exceeds INT_MAX,
or the number of parts exceeds 524288.

ESRCH

The server died while the calling thread was SEND-blocked or REPLY-blocked.

ESRVRFAULT

A fault occurred in a server's address space when the kernel tried to access the server's message buffers.